Adjustable arm or support.



W. ERWIN. ADJUSTABLE ARM 0R SUPPORT.

APPLICATION FILED APILZQ, 1913.

Patented Mar. 3, 191 i WILLIAM ERWIN, OF PHILADELPHIA, PENNSYLVANIA.

ADJUSTABLE ARM OR SUPPORT.

To all whom it may concern:

Be it known that I, l/VILLIAM ERWIN, a citizen of the United States, residing at No. 4844 Cedar avenue, in. the city of Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented a new and useful adjustable arm or device for the support of the head or foot rest of dental, medical, and surgical operating chairs, tables, and similar O'fl'lCG furniture, also for hospital fracture-beds and invalid-beds, where an easily and quickly adjustable support may be needed for suspension or extension apparatus, pulleys, bedside stands or tables, &c.

It is equally suitablegis an adjustable support for telephone, typewriter and similar stands.

The particular advantages of this mechanism are ideal and instant adjustability to a very wide range of positions, under control of a slight turn of a single clamping screw, complete rigidity andimmobility in any and every position to which it may be adjusted, and ideal simplicity of construction, requiring only three patterns for its essential parts.

The accompanying specification, and the drawings which form a part of it, present a clear and accurate description of my invention in one of its applications.

In the drawings Figure 1, is a rear view of the mechanism when extended to its full length; Fig. 2, is a view of the inner side of member A; Fig. 3, is a side view of member B which shows its binding or clamping surfaces; Fig. 4 is a side view of member C; Fi 5, is a side view of the mechanism as applied to the head rest of a dental, medical or surgical chair; Fig. 6, is a rear View, extended to its full length, of an alternative construction which allows lateral adjustment of the rest or support; Fig. 7 is a side view of the end member of the alternative construction.

This device consists of two connected levers, and two end members, together with clamping screw, pivot and retaining pins. Each lever is composed of two members, those of the first lever being parallel and bound or clamped together by a binding or clamping screw placed at or adjacent to their centers, those of the second lever being crossed and pivoted at or adjacent to their centers, the second lever being actuated by Specification of Letters Patent.

Application filed. April 23, 1913.

Patented Mar. 3, 1914.

Serial No. 763,028.

the grasp of the first one, and both levers tightly grasping at their distal extremities the end sections or members.

Members A and A are clamped together by a turn of clamping screw 1), which binds the distal end of each tightly upon (J, which is attached to base 1*), and the proximal end of each upon the outer surfaces of the proximal ends of B and B respectively. Members B and B being crossed and pivoted at their centers are also simultaneously by the same pressure correspondingly bound at their distal ends upon member C, which is attached to rest or support F. The sides of the rounded binding or clampingends of A, A, B, B, C and C present friction surfaces which guarantee rigidity and immobility under pressure. Pins (1, shown by dotted lines, pass through the heads of C and C at c, and enter sockets c in the distal ends of A, A, B and B, which allow a free hinge motion but prevent the l'iinding or clamping surfaces from slipping out of their proper relations. Pins 6, also shown by dotted lines, lit into sockets 0" of the proximal ends of A, A, B and B which articulate with each other, and perform the same function as is done by pins (4.

E represents the top of a chair back to which this support is attached by C, and F represents the back of a head rest as shown in Fig. 5. For other than flat surfaces C and C may be correspondingly shaped to lit. 0 and C are made from a single pattern; A and A are made from a single pattern, and B and B are also made from a single pattern. A differs from A, and B from B only in the finishing of the pivotal points.

Clamping screw 1) passes loosely through A and through A by a screw thread. Nut D, upon the end of l), secured from turning by set-screw c, prevents accidental undue loosening of lovers A, A, B, and B, 1n their liold upon 0, C, and upon each other. When 1) is screwed up its shoulder (Z abuts against A, when further tightening of D clamps A and A firmly against C, and B and B. Pivot bolt G passes through B loosely, and screws firmly into B, thus forming a fulcrum for the leverage of B and B upon C. Either clamping screw 1) or pivot bolt Gr need not necessarily be placed centrally as shown in the drawing, but if desired may be moved either way from the center for the purpose of increasing the pressure in the end toward which it may be approximated. I

In operation the rest or support is held by one hand, and the binding screw D is slightly loosened; the rest is then moved to the exact position desired, D is again screwed up tight, when the rest will remain rigidly fixed in position. In this way the rest may be tilted at any angle desired, or moved upward, downward, forward or backward at will, and instantly fixed rigidly in the chosen position.

In those cases where an added lateral adjustment of the rest or support is desired, the shape of the articulating head of C and C is changed to a ball, as shown by C and C in Figs. 6 and 7 and the distal ends of A, A, B and B are changed to a socket form, which grasp the heads of C and C as shown by A A B and B in Fig. 6. This provides at these points a ball and socket universal joint, which permits adjustment in all directions, and yet secures a rigid and immovable support when D is screwed up tight.

C and C are made from a single pattern; A and A are made from a single pattern; and B and B are also made from a single pattern. A differs from A and B from 13 only in the finishing of the pivotal points.

The operation of the alternative construction is exactly the same as of the regular construction, but it has in addition a lateral adjustment not possessed by the former.

When this device is used for the adjustable support of different rests, pulleys, apparatus, stands, etc, the surfaces of the end members which connect therewith may be variously designed to fit, or when used as a support for stands of various kinds, it may be turned so as to swing laterally and forward and backward, without departing from the principles of its construction and operation as above described.

Having described my invention, what I claim as new, and desire to secure by Letters Patent, is

1. In an adjustable arm or support, two pairs of connected levers,'wherein the members of eachpair are movably and adjustably connected together, the members of the first pair are parallel, controlled by a cen; trally or nearly centrally placed binding or clamping screw, and grasp the members of the second pair, which are crossed for the purpose of continuing or extending compression.

2. In an adjustable arm or support, two pairs of movably and adjustably connected levers, and two end members (attached to ing or clamping screw, and grasp the first end member by their distal ends and the proximal ends of the second pair by their proximal ends, the members of the second pair being crossed, pivoted at or near their centers, and by their distal ends grasping thesecond end member, and wherein all members of said arm or support are rigidly fixed together by the single binding or clamping screw of the first pair of levers, said binding orclamping screw being provided at its end with a detaining nut and set-screw.

8. In an adjustable arm or support, retaining pins, which pass centrally through the heads of the fixed end members or fulcrums of said arm or support, through the centers of the friction contact fixation heads of the proximal ends of the second pair of levers, and enter openings in the centers of the friction contact fixation heads of both ends of both members of the first pair of levers, and of the distal ends of the second pair, and which prevent slipping from re lationship of apposed friction contact fixation surfaces between the movably and adjustably connected levers, and between the levers and the end members thereof.

4. In an adjustable arm or support for a rest for head, foot, pulleys, instruments, or stands of various kinds, the combination of two pairs of movably and adjustably connected levers with two end members, all provided with friction contact fixation connecting surfaces, wherein the first pair of levers are bound or clamped together by a central or nearly central fulcrum binding or clamping screw, and the second pair are reversed or crossed, pivoted upon each other at or,

near their centers, and rigidly bound or clamped together at their proximal ends by the proximal ends of the first pair, so that the distal ends of each pair grasp and rigidly clamp the end members, which are secured to the base and to the rest respectively, and all friction cont-act fixation surfaces are provided with retaining pins.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

' WILLIAM EnwiN.

lVitnesses CLAYTON MoELnoY, THOS. B. RICKETT.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents.

' Washington, D. (3. 

